Perimeter.



W. BERG. PERIMETER.

APPLIOATION FILED APR. 30, 1913. 1, 1 1 3,091

Patented Oct. 6, 19M

2 SHEETS-SHEET 1.

E 353 flttoimey THE NORRIS PETERS ca. PHorc-LlrHou WASHINGTON. L). C.

W. BERG. .PERIMETER.

APPLICATION FILED APR. 30, 1913. 1, 1 13,091; Patented Oct. 6,- 1914.

2 SHEETS-SHEET 2.

THE NORRIS PETERS C0,. PHGTD-LITHO WASHINGTUN. or c.

1,113 091 Specification ofLetters Patent. Patented Oct. 6, 11914.? n 1 Application fiieaa n ao, 1913. Serial No. 764,732. v To all whom itmay concern: a post by an expansion yspring fifresting Be it known that I, WILLIAM BERG, a citiagainst a nut on the end of the pin 3, which zen of the United States, residing at the city s es t e b c will e n in its of New York, in the boroughxof Queens and C JH tBd position. chin-rest 7 of the 1 State of New York, have invented certain usual construction is 'rotatably mounted on? a a new and useful Improvements in 1 Perimesaidvbracket by a similar pin and spring del ters, of which the following is? a full, clear, vice, so that it maybe swung from one side a d exact d i ti 1 a a to another in order to bring each eye of the This inventionfrelates to perimeters and patient in turnopposite the upperend of more especially to the self-registering type. the post. Therear portion ofthe base 1 is y The object of my invention is to construct curved rearwardly as at 8, and then upan instrument of this class which will" be of wardly as at 9, terminating in a horizontal 1 simple and compact form. r a bearing 10, An arcuate frame 11 oompris- Inthe apparatuses whichheretofore have ing a strip of brass or the like which is relabeen constructed, the recordingmeans contively broad and thin, but of sufficient sists of an intricateoonstruction in which strength to form a substantially rigid structhe'elements are liable to get out of adjustture,is attached to a hollow revoluble sleeve ment or to cause an error inthe reading, due 12 fitting inthe bearing10. This sleeve is to lost 1 or inaccurate motion betweenthe enlargedat one end thereofftoj form asupparts. it portingsurface, to which the arc is firmly It is therefore my purposeto construct an secured by screws 14: inset in the surface of 1'75 instrument which will obviate these objecthe arcuate frame. The frame 11 isfprotionsand my invention consists in an instruy vided with a T-shaped groove 15 extending y ment having recording means whose record the entire length of the same in which a ing marker will be moved correspondingly rack 16 is adapted to slide. F astened at the? a j to thetravel of the test object by a direct upper end of this rack is a guide-strap 117 and positive connection between the parts extending across the front surface of the 1 and in which the recordingf marker will frame and around the edges of the same into move in a planefparallel to the plane of engagement with the rear surface. H A colortravel of the arc, the chart-plate being mov shield 18, which carries the test object 19, able and adapted to be brought into position is firmly secured to the strap so that the test where the marker will register the i ccorrect object willbe positively moved by therack, angular position of the testyobject on the The arcuate frame11 comprises a segment chart. i y v Whose peripheral surface extends through n In the accompanying drawings,in which an are somewhat greater than 180 degrees, my improved perimeter is illustrated, Figand the rack comprisesasegment extending to ure 1 is a side elevation thereof; Fig. 2 is a substantially through degrees,so that the jj front elevation; Fig. 3 is a detail of the retest object may have a travel from thecencording mechanism; Fig. i-is a plan of a ter of the field or are to a point at substandetail of therecording mechanism; and Fig. tially 90 degrees therefrom. a 5 is a detail of the profile plate. One of the bent-over portions of the strap The base of the instrument, indicated by 17 is provided with a pointer 17 which is 1, may be of any desired conformation and adapted to ride over a graduated scale 11" is provided with three supporting legs. A on the rear of the arc, wherebythe distance 1 post 2, curved at its lower portion, 1s fasof the test object from the center of the arc tened at its lower end by any desired means Or field may be easily read by the observer. to the front leg of the base; the upper end Aremovable dial 20 having a radial slot 21, of this post acting to position the eye of the fits over the hollow sleeve 12 between its patient, as is common with instruments of support 13 and the enlarged portion of the this type. This post is slotted for the rebearing 10. This dial isheld firmly against ception of a threaded stud-pin 3 carried by, the enlarged end of the bearing 10 by a split gagement with a serrated portion of the unrrnp STATES wr'LLIAM BERG, or nnwvonn, n. Y., ASSIGNOR TO inc n conronn'rroiv OFNEW YORK. y

PERIMETER;

the chin-rest bracket 4. This bracket carspring-washer ries a stop-pin 5, whichis heldqinfirm en- PATENTOFFIGE GENERAL OPTICA COMPANY,

22 which holds the same against rotation with the revoluble sleeve12. A pointer 23, attached to the rearsurface of the rear face of the the arcuate frame, rides over the outer edge of the dial 20 so that the meridian ofthe arc may be read on graduations 24 along the outer edge of this dial. This dial being of relatively large diameter, also serves the additional purpose of concealing the hand of the observer from the eye of the patient. A hollow rotatable shaft 25 fits into the rev oluble sleeve 12 and carries a pinion 26 at its front end, which is firmly secured to the shaft A. circular recess is formed in the center of the arcuate frame in which this pinion seats, the recess cutting one edge of the T-shaped groove, so that the teeth of the rack 16 may be engaged by the teeth of the pinion. A circular plate 27- is provided with a hub 28 which is fitted over the end of the hollow shaft 25 and firmly secured-thereto by a set-screw. WVhen it is desired to move the test object in the field, the observer rotates this 'plate, and motion will be transmitted to the test object through-the mechanism described. I

The recording means receives its-motion through a spiral groove or profile29 cut in plate 27, which, as is clearly shown in Figs. 3 and 5, comprises a spiral having substantially nine completeto' the 90 degrees turns, corresponding object is adapted to through which the test be moved, the purpose of which will be hereinafter set forth. oluble sleeve 12 is a guide bracket 31 which is firmly secured thereto, so that upon rotation of the arc and hollow sleeve, this guide bracket will also be rotated. This bracket is provided with right-angled portions which" extend above and below the circular camplate 27, and has attached to the ends of the same a guidebar 32 upon which the guideblock or traveler v33 is movably mounted.

The bar 32 is preferably rectangular in cross-section and is provided with a circular opening at the center thereof alining with the opening in the hollow shaft 25. The block or traveler 33 consists of a rectangular sleeve which slides onthe guide-bar and has fastened to one side thereof a pin 3st which rides in the spiral groove 29 of the plate 27. It will therefore be seen that uponone revolution of the circular plate 27 the guideblock 33 will be moved a distance equal to the distance between the centers of two adjacent grooves.- A marker such as a pencil or prick-pin 35, fastened-to a metallic strip, I

' which openings determine the po nt at which slotted for the receptionof a set-screw, is adjustably mounted on the rear face of the rectangular guide-block 33 for engagement with a chart which is preferably supported in the following manner. Extending sub stantially at right angles to the vertical portion 9 of the frame-is a support 36 for the chart-plate 37. This plate is firmly fastened to a skeleton frame 38 by means of the pins 39, the two free ends of the frame being Mounted on the revbeyond this point.

1s provided with cuts or gage-marks 43, which define" the vertical and horizontal axes of the plate and. with which the horizontaland vertical axes of the chart should be alined for a purpose which will hereinafter bedescribed in connection with the operation of the instrument.

In using the perimeter, a chart is firmly positioned upon the chart-plate with its I horizo-ntaland "vertical axes alining with the,

The test 'obgage-mark 43 on the same. ject is moveduntil it is directly at the center or zero point of the arc, 2'. 6., when pointer 17 isat zero point of the graduated scale 11 on the rear surface of the arc. The marker 35 having a corresponding move ment, should now be positioned so that when the chart is brought into engagement with the same, a point will be recorded at the exact center of the chart. If the point is olfcenter, the marker may be adjusted until exact registry is obtained, by means of the set-screw which holds the marker in place. After the marker or prick-pin has once been adjusted, it is only necessary to aline' the vertical with the gage-'marks 43 cm the plate to insure that the centers of the'arc and chart and horizontal axes of the chart tat'ed to bring the axes ofthe arc and'chart into parallelism. When the marker or pin 35 isat the center or zero point of the arc,

it is to be'noted that the pin34i will not be seated in the end of the groove for this groove is continued for a portion of a turn If the operator should then carelessly move its zero position, the same will not be the test object. toward stopped until it has passed by thezero point a distance suflicient to warn the operator of this fact, which will diminish the chances of the pin 34 being forced against the end of the groove hard enough to break or bend the same. The chin-rest is then adjusted to bring the eye of the patient upon an exact horizontal axis determined by the circular openings in the hollow shaft and guide-bar,

the eye of the patient is to be directed and is usually known as the fixation point.

Assuming now that the arc is in a horizontal plane so that the pointer 23 will register with zero graduation on the large dial 20, the test object will then be moved by revolving the cam-plate 27. The rack and pinion are so designed that upon one revolution of the cam-plate 27, the test object will move therefore so frame will be reproduced by the marker 35 a of the range of Vision until points have I been moving along its guide-bar 32, so that upon bringing the chart into engagement with this marker, the exact angular distance which the testobject has been moved will be recorded. After a predetermined point has been recorded in thehorizontal plane, further be, described but of the patients which need not will determine the extent range of vision along th1sjajxis,the arcuate frame 11 is then moved tofvarious other In each position a point determine the extent angular positions. is recorded which w ll determined for the entire angular movement of theme from which the field of vision of the patient may be plotted. After one eye of the patient has been tested, the chin-rest 1s swung to the other side and the other eye is tested in a similar manner. I desire to Particularly emphasize that since thelguide-bracket is positively connected to the hollow sleeve carrying the arcuate frame 11, there is no possibility of any lost motion between these two parts, and as the pin 3i fits closely within the spiral groove, an error due to lost motion from this source isviprecluded. It will also be obvious that the recording means is of marked simplicity, having no parts which necessitate fine adjustment to obtain precise measurements, making it possible to produce an accurateinstrument of this type at a materially decreased cost.

Having thus described my invention, I claim i i i i 1., In aninstrument of the class described, a revoluble are, a test object movably mounted thereon, means for moving said test object including a rotatable member, revoluble with said are, recording means having a marker, and means operatively associated with said marker correspondingly to the movement member for moving said of the test object.

2. In an instrument of the class described, an arc revolubly mounted on a hollow sleeve, a rack slidably mounted on said are and carrying a test through said hollow sleeve having a pinion in engagement with said rack, means for rotating said shaft, and means operatively ELSSOCiiItBClWltlI said meansfor recording the position of the test object. a

3. In an instrument of the class described,

will be moved the distance of therecording mechanism are along that meridian object, a shaft passing the combination with a revoluble arc having a movable ltestobject mounted thereon, means for movlng said test ob ect,1neansfor recording the position of said test object including, a rotatable member connected to said first named :means having, a spiral groove in the face thereof, and acmarker adapted totravel in said groove.

4. In aninstrument of the class described, acrevoluble are, a rack slidibly mounted thereon carrying a test object, a pinion and a rotatable member connected thereto for moving said rack, said pinion and rotatable member being revoluble with said are, and recording means also revoluble with said are having a movable marker operatively associated with said rotatable member for moving said marker correspondingly with the movement of said test object.

5. In an instrument of the class described,

a revolubly mounted are, a test object movably mounted on said arc, shifting means therefor, a recording mechanismineluding a marker connected to said shifting means and arranged to be revolved with said are and to be moved correspondingly to the movement of the test object both of said movements tially parallel to the said arc.

6. In an instrument of the class described, an arc revolubly mounted on a hollow sleeve, a rack movably mounted on said are carrying a through said hollow sleeve plane of rotation of said shaft provided with a spiral groove, recording means, means for supporting the same, said supporting means beingvrevoluble with said are, and means co-acting with said spiral groove for moving said recording means correspondingly with the movement of the test object.

7. In an instrument of the class described,

a revolubly mounted are, a rack carrying a test object slidably mounted ion engaging with said rack for movlng the test object, a rotatable member connected to said pinion and revoluble with said are, and means co-acting with said rotatable member for recording the position of the test object in the field of vision.

8. In an instrumentof the class described, an arc revolubly mounted on a hollow sleeve, a rack slidably mounted on said are carrying a test object, a shaft passing through said hollow sleeve havlng a pinion thereon for engagement wlth said rack, and

a marking device revoluble on an axis parallel to the axis of rotation of said are and connected to said shaft for moving said test object, a shaft passing having a P1111011 for engagementwith Silld rack, means on thereon, a pin-t Sa M beingin a plane substanmarking device correspondingly with the movement of said test object.

9. In an instrument of they class described,

the combination with a movable test object and means'for moving thesame'toanypoint 1 In Witness whereofll subscribe my signa- Wit in the field of vision; and= means for ture-inthe presence of two Witnesses. recording the position of the test; object comprising a rotatable plate connected to WILLIAM =said fi rst named means, said plate having Witnesses:

a spiral groove therein and; a marking de- E. J; WOHRLE, vice adapted to travelin said gr0ove.- J. L. GOLDSTEYINQ Copies ot this -patenfimay =b'e obtafiiedforfive cents each, by addressin Washington, D. 0.

g the commissio ner of Patents, 

